For a patent claim to be entitled to the priority date of an earlier patent application, the earlier patent specification must reasonably convey to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc). It is not enough that a claimed invention is “an obvious variant of that which is disclosed in the specification.” Lockwood v. Am. Airlines, Inc., 107 F.3d 1565, 1572 (Fed. Cir. 1997).

There is sufficient written description support when “the specification describes a reason to exclude the relevant [element].” Santarus, Inc. v. Par Pharm., Inc., 694 F.3d 1344, 1351 (Fed. Cir. 2012); Inphi Corp. v. Netlist, Inc., 805 F.3d 1350, 1355 (Fed. Cir. 2015) (same). A reason to exclude an element could be found in “statements in the specification expressly listing the disadvantages of using” that element. Santarus, 694 F.3d at 1351. Another reason could be that the specification “distinguishes among” the element and alternatives to it. Inphi, 805 F.3d at 1357; see also In re Johnson, 558 F.2d 1008, 1017–19 (C.C.P.A. 1977) (reversing rejection for inadequate written description where specification disclosed several species of a genus and claims recited genus but excluded two species of lost interference count).

Recently in Novartis Pharms. Corp. v. Accord Healthcare, Inc., No. 20-1070, 2022 WL 2204163, — F.4th — (Fed. Cir. Jun. 21, 2022), the Federal Circuit addressed claimed methods of treating relapsing-remitting multiple sclerosis (RRMS) through the administration of fingolimod (an immune suppressant) “at a daily dosage of 0.5 mg, absent an immediately preceding loading dose regimen.” The “no loading dose” limitation was added by amendment during prosecution in order to overcome an obviousness rejection. A loading dose is a “higher-than-daily dose,” often given as the first dosage in a dosing regimen. There was no dispute that loading doses were well-known in the medical field generally, and specifically in the treatment of multiple sclerosis with some medications.

The earlier priority application, however, did not explicitly discuss not using loading doses. But the district court had found implicit support for the negative claim limitation in two examples provided in the specification which disclosed dosage regimens that did not involve the use of an initial loading dose. There was expert testimony that a person of skill in the art would have understood the fact that the examples do not mention a loading dose as implicitly disclosing a dosage regimen that is not preceded by a loading dose.

In a 2-1 decision, the Federal Circuit panel found that the district court erred in finding written description support for the “no loading dose” limitation because there was no evidence that a skilled artisan would understand silence regarding a loading dose to “necessarily exclude” a loading dose. See Tronzo v. Biomet, Inc., 156 F.3d 1154, 1159 (Fed. Cir. 1998) (“[M]issing descriptive matter must necessarily be present in the … specification such that one skilled in the art would recognize such a disclosure.” (citing Cont'l Can Co. USA v. Monsanto Co., 948 F.2d 1264, 1268 (Fed. Cir. 1991))); see also In re Robertson, 169 F.3d 743, 745 (Fed. Cir. 1999) (discussing inherency for purposes of anticipation requires that the missing descriptive matter would be so recognized by persons of ordinary skill).

Citing Seabed Geosolutions (US) Inc. v. Magseis FF LLC, 8 F.4th 1285, 1288 (Fed. Cir. 2021) (“[S]ilence does not support reading the claims to exclude gimbaled geophones.” (citations omitted)), the Court stated, “Silence is generally not disclosure.”

While a written description's silence about a negative claim limitation is a useful and important clue and may often be dispositive, it is possible that the written description requirement may be satisfied when a skilled artisan would understand the specification as inherently disclosing the negative limitation.

The dissent by Judge Linn, on the other hand, framed the question as “whether the claim language that precludes the administration of a loading dose is supported by the written description passages that disclose the effective administration of nothing more than a ‘daily dose.'” Under the framing of this question, rather than looking for a patent disclosure that precluded the use of a loading dose, a disclosure that “implies the absence of a loading dose to the ordinarily skilled artisan” would have been sufficient in view of the expert testimony about what one of ordinary skill in the art would have understood.

Interestingly, this 2-1 decision was the result of a rehearing, but Judge O'Malley, the judge who wrote the original Novartis opinion (also a 2-1 decision) in January 2022 upholding the district court's decision, had retired in March. Another judge was assigned to the panel for rehearing. That reconfigured panel then came to the opposite conclusion in a 2-1 decision going the other way. And Judge Moore (the dissenting judge in the original decision who originally wrote in dissent: “Silence is not disclosure”) wrote the new decision on rehearing.

Luck of the draw.